I installed pulleys on my 04 gt last week, I started hearing a humming sound but i am not sure, I just got the car and havent really listened to it run with the hood open until i put the pulleys on, I cant hear it from the inside. Also it looks like the harmonic balancer might be wobbling a little, but i was thinking it was just the engine shaking at idle. Anybody heard of these problems or do i need to find a new hobby besides working on my car?

 

The BBK U/D pulleys are the piggyback type.This means that the old,stock balancer must be used with the new pulley.The wobble you describe is fairly common on these installations.Try loosening the bolts and trying to get the old balancer to seat properly or you might just have to live with it.Or if you can't stand to see your crank being destroyed by an unbalanced condition,get some Steeda pulleys and be done with it.